I feel so stupid ಠ_ಠ

Now I know why I2C was not working in my nixie clock. Today I got an arduino nano from helsinki hacklab, and started to troubleshoot my circuit. Oddly RTC worked when I tried it in breadboard, and also in clock’s motherboard, when nothing else were connected. Also noticed that when nixie driverboard was connected, both of the i2c lines had weird resistance to 5v and ground. I once again removed driver board from case and measured. It was ok, of course. I didn’t even tough about cabling <.<I had used old weird 3 pair ribbon cables which, when inspected, have one layer of black conductive plastic. Unfortunately I had crimped connectors so that conductive layer shorted pairs, not total short circuit but 500-1k ohm resistance between each wires. Well, now it is working perfectly good, even tough it still shows (I need to check addresses etc) nothing. But maybe this project is not doomed. And Arduino is very handy for quick prototyping and troubleshooting etc.